# 输出了字符串中所有子字符串
def all_son_str(s):
    result_list = []
    s_len = len(s)
    for i in range(s_len):
        for n in range(i + 1, s_len + 1):
            son_s = s[i:n]
            result_list.append(son_s)
    return result_list


s = "avcd"
print(all_son_str(s))
